fix: properly validate hmac strings #40

Job	Run time
test-on-deno-and-lint (ubuntu-latest)	12s
test-on-bun (ubuntu-latest)	12s
test-on-deno-and-lint (windows-latest)	23s
test-on-node (20, ubuntu-latest)	24s
test-on-bun (windows-latest)	40s
test-on-deno-and-lint (macOS-latest)	15s
test-on-node (20, windows-latest)	1m 53s
test-on-bun (macOS-latest)	10s
test-on-node (20, macOS-latest)	21s
test-on-node (22, ubuntu-latest)	28s
test-on-node (22, windows-latest)	1m 37s
test-on-node (22, macOS-latest)	23s
test-on-node (23, ubuntu-latest)	15s
test-on-node (23, windows-latest)	3m 1s
test-on-node (23, macOS-latest)	26s
	10m 40s

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